"'map' was not declared in this scope"

Projects Programming
1

Hello. I have this problem with map() not really being recognised it seems. If it matters, I am using Arduino IDE 1.8.1, and a MEGA 2560 board.

Currently I am trying to make a class work,

DSDroneSignal.h

#include "Config.h"

class DSDroneSignal
{
 public:
  //DSDroneSignal();    // Constructor set default ppm-values
  void EditControl(char InputSegment[]);
  void ChangeVelocity(int Channel, int Value);
 private: 
  int PPM[CHANNEL_NUMBER];
};

and DSDroneSignal.cpp,

void DSDroneSignal::EditControl(char InputSegment[])
{
  if ( InputSegment[0] == ( ('t' || 'r' || 'a' || 'y') || ('T' || 'R' || 'A' || 'Y') ) )
  {
    // TODO: Make channel recogniser-function instead,
    int ChannelIndex = 1;
    int VelocityRate = atoi(&InputSegment[1]);
    int NewVelocity = map(VelocityRate, 0, 100, CHANNEL_MIN_VALUE, CHANNEL_MAX_VALUE);
    
    DSDroneSignal::ChangeVelocity(ChannelIndex, NewVelocity);
  }

};



void DSDroneSignal::ChangeVelocity(int Channel, int Value)
{
  DSDroneSignal::PPM[Channel] = Value;
};

And I get this error,

sketch/DroneSignal.cpp: In member function 'void DSDroneSignal::EditControl(char*)':
DroneSignal.cpp:11: error: 'map' was not declared in this scope
     int NewVelocity = map(VelocityRate, 0, 100, CHANNEL_MIN_VALUE, CHANNEL_MAX_VALUE);

Inside of the Config.h file are the capitalised constants given as well as the standard library included (<stdlib.h>).

I dont' really see anyone having this problem except for one guy in 2008, because map() was recently introduced back then, and he had not updated his software. Now, I am borrowing this Arduino from someone else, but I doubt it is that old.

2

You need to include Arduino.h. We're used to having access to all the Arduino core library functions in our sketches because the IDE automatically adds the line:

#include <Arduino.h>

to the sketch when you compile but it does not do so for other source files.

3

Ah, that makes sense, and it seems to work now. Thank you very much for the help!

4

if ( InputSegment[0] == ( ('t' || 'r' || 'a' || 'y') || ('T' || 'R' || 'A' || 'Y') ) )This is not how you compare a value with one or more other values. You need to do the comparisons individually or iterate through a string looking at each character in turn.

5

Following on Bob's comment, you might use:

   char testInput[] = "TRAY";

   // more code...

   for (i...
      for (j...
         if (toupper(InputSegment[i]) == testInput[j]) {

The toupper() macro makes it so you can abstract from upper and lower case letters.

6

Hello. Sorry, I thought I had replied. Thank you for the tips, both of you. It's been a while since I've done C++. With my school work, you pretty much only work with high level programming/scripting, so I don't really get to work with not-so-forgiving code too much anymore.